This article was originally published on WeedWeek, and appears here with permission. How to Grow Hydroponic Cannabis at Home Hydroponics is when you grow your cannabis plant in an inert medium like coco or a reservoir of water, and provide all the nutrients to the plant directly Learn how to best use hydroponic growing systems and techniques to cultivate cannabis and how these techniques can improve your crop.
Hydroponic Cannabis: A Guide To Hydroponic Weed And How To Grow It
This article was originally published on WeedWeek, and appears here with permission.
Hydroponic cannabis is a fascinating and effective way to grow marijuana. There are many different ways to grow weed hydroponically, ranging from huge commercial operations to a simple garden in your closet. This article will explore the different to grow weed hydroponically, what some of the advantages are, and what you’ll need to get started on a hydroponic garden of your very own.
What Is Hydroponic Cannabis?
Hydroponic cannabis refers to plants that are grown in a nutrient-rich water solution instead of soil. Hydroponic cannabis can be grown in a variety of different ways, using mediums ranging from clay pellets to only air, or in deep water buckets or even with fish. But you will not find soil as part of any hydroponic grow.
Differences Between Soil & Hydroponic Cannabis
Soil is composed of organic materials found on the Earth’s surface, composed of decaying detritus (fallen leaves, insect and animal corpses, and so on).
Plants, including cannabis sativa, naturally grow in soil. However, it is also possible to grow plants in widely differing mediums that involve no soil at all. These are hydroponic methods of growing. Rather than roots embedding themselves into soil as they search for and absorb nutrients, a hydroponic grow provides a nutrient-rich, water-based solution that is applied directly to roots, enabling more efficient uptake.
The Advantages Of Hydroponic Cannabis Growing
Growing cannabis in soil has its advantages, but with hydro, plants can grow taller, grow faster and provide larger yields. In soil, the roots of plants must search for the nutrients they need for growth. With a hydroponic setup, the nutrients are much more easily available and accessible, allowing the plant to divert more energy into stem, leaf and flower growth.
How To Grow Hydroponic Marijuana
Growing hydroponic marijuana requires a bit more of a setup than a simple pot on your balcony. There are many hydroponic systems available that can suit any need – from beginner to more professional. The Viagrow Complete Ebb & Flow Hydroponics System comes with a table, space for 14 plants and an automated delivery system for water, nutrients and oxygen. More simpler kids, such as the Deep Water Culture Hydroponic Bucket is easy to use and includes water level indicators, rockwool starter plugs and an air pump.
But you can also go the do-it-yourself route which, although initially a bit more intensive to set up, can allow you to tailor your setup to your personal needs.
Royal Queen Seeds provides the following list of equipment you’ll need for a do-it-yourself setup.
Choose A Growing Medium
There are many growing mediums to choose from with regards to hydroponic marijuana grows. Below are a few of the most popular.
Plant roots are meant to be submerged in soil, however, they can also grow in the air. With air grows, roots are misted with water and nutrients, which allows for plenty of oxygen and no drainage issues. The one danger is that the plants are utterly reliant on you paying close attention or, if you’ve got an automated grow, the power staying on – an outage could cost you your plants.
Clay pebbles are porous, speckled pieces of clay that resemble dog kibble. Clay pebbles are perfect for delivering high quantities of oxygen for roots, retaining high amounts of nutrients and water, and allow for drainage as well.
As the name suggests, coco coir is ground-up husks of coconuts, and are an increasingly popular choice for hydro grows. A coconut husk is designed to protect the inner flesh from harsh external factors and, most importantly, serves as a perfect germinating medium for a new coconut tree. Coco coir provides all of these benefits to your marijuana plants.
Perlite is volcanic glass that has been infused with air, creating a porous material with high oxygen retention capabilities. Perlite is often added to soil mediums to boost aeration levels. This material is a great solution for hydroponic grows, although pay extra attention to water levels since perlite retains no water whatsoever.
Rockwool is material made from melted rock fibers, similar to that of fibreglass. Although this material has been around for a long time, it comes with some downsides, including potential health hazards associated with inhaling dust from dried rockwool (the solution being to immediately drench the rockwool in water). Rockwool also comes with a relatively high pH that must be balanced. On the plus side, rockwool is an excellent water retainer.
Vermiculite has a pebble-like texture that retains water well, capable of drawing water and nutrients upwards (also known as “wicking”). While it can be expensive and can sometimes hold too much water, vermiculite is great for using in combination with other grow mediums, enabling you to tailor your medium to your specific setup.
Choose The Right Hydroponic Grow System
Choosing the right hydroponic growing system is an important step. Be sure to take into consideration your level of expertise, how much money and time you’re willing to spend, and how many plants you’d like to include in your garden. Below are a selection of the most popular hydroponic grow systems to consider.
In an aeroponic grow, no growth medium is used, allowing the roots to hang free. The nutrient solution is delivered via an aerosolized spray, creating a nourishing mist for the roots. The advantage to this misting technique is that it helps with nutrient absorption and uptake, which translates into bigger, faster plant growth.
If you were one of those kids who had an aquarium in your room, you were halfway to an aquaponic grow without even knowing it. Plant roots are submerged into a tank of water that also contains living fish. As a closed-loop system, nutrients for the plants are not added in – rather, they are produced by the fish themselves as waste. As the plants absorb the fish waste, they in turn purify the water in which the fish live.
Deep Water Culture
A characteristic feature of a deep water culture hydroponic grow is the reservoir that can hold a large amount of water. Bigger volumes of water help enable a more stable nutrient solution, releasing you from the duty of watching nutrient levels on a continual basis. A deep water culture requires most of the root mass be submerged in water all of the time. Overall, this method promotes fast plant growth and is relatively easy to set up.
Using a soilless medium, a drip system uses the popular irrigation technique of nutrient delivery via drip emitters, which mimic a light rain. There is generally one drip emitter per plant, delivering nutrients directly to the roots.
Ebb & Flood
The ebb and flood method uses a coarse growth medium, allowing roots to grow relatively freely with plenty of space and oxygen, increasing growth and yields. The nutrient solution is flooded over the roots, saturating the medium, while the reservoir is placed on a lower level which allows the solution to then flow back to the reservoir. This flooding needs to be done three times a day, which is why automated systems are a preferred choice for the ebb and flood method.
The aerated solution method is similar to the ebb and flood method but recommended for those who aren’t using an automated flooding system and who can’t be available to flood three times per day. Rather than a reservoir, the aerated solution uses an aquarium aerator, making it possible to aerate the medium and provide a constant fresh supply of nutrient solution.
Nutrient Film Technique (NFT)
What makes the nutrient film technique stand out is that it doesn’t use a growth medium, allowing plant roots to grow extensively. Roots are constantly exposed to the nutrient solution via a fast-flowing, aerated currents, providing continual nourishment and oxygen. This method is ideal for larger-scale commercial grows.
Nutrients For Hydroponic Cannabis
When looking for nutrients for your hydroponic cannabis, it’s important to select products that are tailored specifically for hydroponic grows. Do not use nutrients made for soil (products made of organic materials like guano or blood meal) because these nutrients can upset the delicate balance of the reservoir and potentially cause problems with the roots.
Hydroponic nutrients are those provided by minerals that have been “chelated”, meaning they are rendered easier for plant roots to absorb. You’ll want to use nutrients with a proper nitrogen-phosphorus-potassium balance – look for a 2-1-6 balance on the label. Aside from NPK, check for sulfur, iron, magnesium and calcium for optimal results.
The Cost Of Growing With Hydroponics
Costs of growing with hydroponics will vary based on your setup. Some factors to consider are electricity (which will vary based on the type and strength of your lights), space rental (which can be your closet or somewhere in your current living situation to cut down on costs), water, nutrients and CO2, and additional materials you might require, such as pesticides. One estimate puts a nine-week crop (meaning more than one plant, and bringing plants from seed to harvest) at around $3500.
The History Of Hydroponics
With all the trappings of modern technology, hydroponics may seem to be a relatively recent innovation. In fact, the opposite is true. People were growing plants hydroponically as early as 600 BC, in the famed Hanging Gardens of Babylon. These gardens were developed in response to dry, arid climates, where plants were watered using an irrigation-type system with water from the Euphrates River. The Aztecs in Mexico were also using hydroponic systems during the 10th and 11th centuries CE, as was China in the late 13th century.
In many ways, growing hydroponic cannabis is a superior method to growing in soil. Although there is a bit of a learning curve and sometimes a financial investment in order to get a hydro garden up and running, hydroponic marijuana can wind up producing a bigger, better harvest. It’s no wonder that, with a history dating back thousands of years, hydroponic is a preferred choice for many pot growers around the world.
How to Grow Hydroponic Cannabis at Home
Hydroponics is when you grow your cannabis plant in an inert medium like coco or a reservoir of water, and provide all the nutrients to the plant directly in the water.
Growing in coco coir can be considered a type of hydroponics since it naturally contains no nutrients and you must provide all the nutrients in the water. However, when you say “hydroponics” most people think of this:
When it comes to hydroponic cannabis…
Differences Between Soil & Hydro
- The optimum pH for coco and hydroponics is 5.5-6.5, while the optimum pH for soil is 6-7
- Nutrients must be provided from when a hydroponic plant is a seedling (in seedling doses to start), otherwise the seedling will grow slower because it only has what’s contained in the seed itself. In soil you don’t need to add nutrients for a few weeks since there’s already some in the soil
- Growing in coco coir (a growing medium that looks somewhat like soil but is actually made of dried coconut husks) gives you results that are somewhat between growing in soil and growing in a hydroponic reservoir of water – you get a lot of the benefits of both
Pros of Hydro
- Plants in hydroponic setups generally grow faster in the vegetative stage than soil-grown plants
- Less likely to get bugs
- Buds can feel more potent
- If growing in a reservoir you don’t have to worry about watering your plants when they’re dry, over/under watering, or removing runoff. Everyone is different but I find maintaining a hydro reservoir easier than moving the plants around or watering and using a wet vacuum to remove runoff (but we all have our personal preferences!)
- If growing in a reservoir you use a very efficient amount of nutrients since you only mix up new water a few times a month, and only toss old water after the plant has already used up a lot of nutrients, which can save quite a bit if you’re using expensive nutrients and is better for the environment (compared to drain-to-waste)
- You have more control over nutrient levels, PPM, and pH – for the mad scientists among us who want to get the most out of our plants as possible!
Cons of Hydro
- Hydro usually takes more preparation/setup than growing in soil. You’re providing more for the plant instead of letting the soil do some of the work for you
- It can be easy to get root rot in hydro if you don’t provide your plant with a good-bacteria supplement like Hydroguard.
- Soil-grown buds may have a more complex or stronger smell than hydro-grown buds, especially if grown in composted living soil without any liquid nutrients
- Growing in soil is more intuitive for many people, and some people already have experience with soil from other types of gardening!
Is Hydroponics Good for Growing Cannabis?
Have you seen cannabis plants growing with their roots just floating in a reservoir of water? This type of hydroponics is known as Deep Water Culture (DWC), and has been around for over a 100 years! As more growers gain experience with this medium, DWC has become increasingly popular for growing cannabis. Hydroponic setups are really neat and offer some big benefits over growing in soil!
Benefits of Hydro Over Soil
- Plants grown in a hydroponic reservoir tend to grow faster in the vegetative stage, resulting in bigger yields and faster harvests
- Hydroponic buds tend to be more potent and often cost more at dispensaries
- Once a hydroponic reservoir is set up, it does not take a lot of work or time to maintain. Instead of regularly watering plants and removing runoff, a hydro reservoir only requires you dip a PH Pen and top off with more water or adjust as needed.
Cons of Hydro
- Takes more time and effort to set up than soil or coco
- Buds grown in soil without added nutrients tend to have a stronger smell than buds grown with liquid nutrients like in a hydroponic setup (though if you’re trying to keep things low odor this might be a benefit).
- Unless you protect your roots by using the right supplements and equipment, your plants may struggle with root rot. Luckily if you follow the steps in this tutorial you don’t need to worry about root rot killing your plants!
Hydro is a no-brainer for me. Whenever I go back to a hand-watered grow like coco coir, I am always surprised by how much extra time it takes to water plants and remove the runoff. The most intimidating part of hydro is just getting started – after that it’s actually really easy to take care of your plants. In my opinion, hydro is far easier and less time consuming than growing in soil or coco coir once you’re set up. If you are interested in hydro, go for it! If you follow this tutorial you will succeed!
Today I’ll teach you how to set up your hydroponic reservoir for growing cannabis, and I’ll show you what you need to do each day for optimum growth
How to Grow Cannabis in DWC
So there are five major parts to getting set up. You need….
- Grow Environment – I personally recommend a grow tent as opposed to building your own environment from scratch.
- Grow Light – If you don’t already have a grow light, I recommend getting a 250W, 400W or 600W HPS grow light for your first grow. They are the most consistent type of grow light and get really great results in DWC.
- Nutrients – I highly recommend getting GH Flora trio, Calimagic (Cal-Mag supplement) and Hydroguard.
- Seeds – Learn where to get seeds
- DWC tank – Learn how to build your own (it’s surprisingly hard to find a pre-made tank considering how cheap all the parts are!)
Once you’ve got your gear and supplies, it’s time to get set up and start growing! Here’s a quick overview.
How to Grow Hydroponic Cannabis
I n the previous post, we gave an overview of hydroponic gardening including its origins, the various systems and techniques, and medium options for a hydroponic grow. In this next article, we will focus how to use hydroponic systems specifically for growing cannabis.
What Is Hydroponic Cannabis?
The common nickname for cannabis—“weed” —comes from its ability to grow almost anywhere, under varying conditions and different climates. “Hydroponic cannabis” simply refers to plants grown using a nutrient-water solution and an inert growing medium rather than nutrient-rich soil. This method could be something as basic as hand-watering pots of inert medium with a nutrient solution. As discussed in the first part of this series, sophisticated systems with multiple pumps, timers, and reservoirs can take some of the daily labor out of growing, but they require more maintenance and setup time as well as a greater initial investment.
Cannabis growers have been using different hydroponic methods for many years as a way to maximize yields and speed up growth, the two main advantages of soilless growing. Working with soils indoors can be inefficient and difficult for a number of reasons:
- You may not be able to recycle soil
- Susceptibility to pest problems
- Difficult to determine proper amount of nutrients
- Need to carefully monitor soil pH
- Soil quality significantly influences the final product
With some hydroponic methods, you get to use small amounts of grow media that can often be reused while also precisely controlling what nutrients the plants are receiving and pH levels. With such levels of control, growers find that their buds are bigger, healthier and more potent.
Whether you have grown cannabis before or have no experience growing cannabis whatsoever, hydroponics can be a great way to produce cannabis in any size space. At first it can be confusing and slightly overwhelming, but by learning the basics you will come to understand it’s not as difficult as you imagined.
Set Up Your Hydroponic Cannabis Growing System
There are numerous setups for growing hydroponically with varying benefits that were discussed previously here. And while there are several types of hydroponic setups that don’t use any type of growing medium at all, many of them still use some sort of substrate to support root growth.
Various materials all provide slightly different benefits and drawbacks, so some thought should be put into choosing the right medium for your cannabis plants. In this article, we are going to be utilizing the drip line hydroponics technique.
While this system is built from the ground up, it should be noted that there are plenty of plug and play systems available for those looking for something that is easy to set up. Plug and play systems come with everything you need in a streamlined package to allow growers to get started on the right foot.
First we will start with the supplies needed. Keep in mind this is just an example, and depending on your space and desired results, many things can be tweaked in a hydroponic system to make it most beneficial to you. This list specifically outlines equipment needed to install your hydroponic system and does not include lights, fans, filters, and other basic needs for any grow room.
Hydroponic Cannabis Supplies:
- 3 or 5 gallon bucket (one for each plant)
- Grow table
- Clay pellets (enough to fill each bucket)
- Rockwool cubes (one 1.5-inch starter plug per plant)
- Reservoir tank (depending on the size of garden)
- Water pump (the bigger the better)
- Air pump
- Air stone
- Plastic tubing
- Drip line
- Drip line emitters (one or two per plant)
Browse Hydroponic Growing Supplies
Once you have gathered your materials you can begin to construct your hydroponic setup.
- First, set up your reservoir. Your reservoir is where your nutrient solution is held. A reservoir can come in all shapes and sizes depending on your grow space and size, and it holds the water pump and the air stone. It will have a line in from the air pump to the air stone and a drainage line in from the grow table. The reservoir will have a line out from the water pump to the drip line and the power cord for the water pump.
- Next you will create your grow table. The purpose of the table is to contain and return the excess water from the plants to the reservoir. To do this successfully, the table needs to have a low point where all the excess water will travel to. This low point is where you install the drain that will take the water back to the reservoir via plastic tubing.
- You can then add your 5 gallon buckets filled with clay pellets on the table. Before using clay pellets, you should soak the pellets overnight to allow them to become fully saturated with water for your plants to drink. Also, the buckets need to have holes drilled in the bottom to allow them to drain excess water onto the grow table. It is important that the holes are about half the diameter of the clay pellets to prevent the pellets from passing through or clogging the holes.
- Take the plastic tubing coming off of the water pump and run the line to the grow table. From here you can use drip line equipment to puncture holes in the plastic tubing and extend drip line to each bucket. Finally, attach drip line emitters to the end of the drip lines.
- From here you can run your system without plants to see if everything is functioning properly. The system should not have standing water anywhere. The air pump should always be running to keep the water in the reservoir oxygenated and moving, while the 5 gallon buckets and grow table drains any excess water back into the reservoir.
- At this point you are setup and ready to create your nutrient water solution in your reservoir. Below we will introduce information about nutrients and how to use them to grow your cannabis plants.
- Once your solution is ready, can introduce your plants. Take the starts or clones that have begun growing in rockwool and place them into the clay pellets. Insert the drip line so that moisture is reaching the rockwool and roots of your starts.
A benefit this setup offers is that it can easily be expanded as you want to grow more plants as long as your reservoir has enough capacity to provide all the plants with enough water. To expand a drip line setup, all you need to do is add additional lines to the new pots.
Nutrients for Hydroponic Cannabis
When growing hydroponically, you are responsible for providing all of the nutrients necessary for plants to survive. Nitrogen (N), Phosphorus (P), and Potassium (K) are the three essential nutrients for plant growth known as macronutrients. Additionally, there are secondary and micronutrients that will help the plant develop as well. These include Boron, Calcium, Copper, Iron, Magnesium, Sulfur, and Zinc.
Many companies sell hydroponic nutrient solutions that are specifically designed for certain stages of growth. Nitrogen-rich nutrient solutions will be used in the vegetative stage while phosphorus-rich nutrients become more necessary in the flowering phase.
Nutrients will come either pre-mixed in a solution or in powder form. While powder form might be cheaper and less bulky, it is best to stick with liquid pre-mixed nutrients if you are a small-time grower as they mix with water easily and are more forgiving.
Explore Nutrients for Your Hydroponic Cannabis
When mixing in nutrients, take a few measurements to make sure your solution is safe for the plants. First, make sure you have the right EC (electrical conductivity) reading, and secondly, ensure your pH reading is correct.
The EC reading is how growers can tell how strong their solution is, and how mineral-rich the water is. The more minerals, the higher the EC rating will be. Generally speaking, a reading between 0.8 to 2.0 is appropriate for growing cannabis. When a plant is young, it will need a lower amount of nutrients as opposed to when it is flowering and growing quite big.
Another common measurement used is ppm (parts per million) which is another way of looking at how nutrient-dense your solution is. There are two different scales for ppm used in the cannabis industry: the 500 and the 700 scale. The most efficient way to determine ppm is to take an EC reading, multiply it by either 500 or 700 depending on the scale you are using. An EC reading of 2.0 would equal either 1,000 ppm (500 scale) or 1,400 ppm (700 scale). Many readers used to measure EC or ppm will do this conversion for you.
The lower the ppm, the less nutrient-dense a solution is. As a general rule, aim for the following densities based on your plant’s age:
- Seedlings/early sprouts – 100 to 250 ppm
- Early vegetative stage – 300 to 400 ppm
- Full vegetative stage – 450 to 700 ppm
- Early blooming stage – 750 to 950 ppm
- Full mature bloom/ripening stage – 1,000 to 1,600 ppm
Note what scale the nutrients you are using are based upon before making any nutrient solutions.
Next, you’ll need to balance the pH level. Between 5.5 and 6 is ideal for cannabis to absorb the nutrients. If levels are off significantly, the plants will fail to uptake the nutrients and will suffer deficiencies.
You should continue to monitor your solution by taking readings two times a day to make sure everything is at the correct levels. Regardless, it is good practice to switch out your solutions every week or two to keep the solution as optimal as possible.
Caring for Cannabis Grown With Hydroponics vs. Soil
Raising a plant with hydroponics is different in many ways from growing in a soil garden. One thing to consider is the support the plant is receiving. Unlike a plant growing in soil, plants in hydro mediums might be vulnerable to tipping or breaking. Trellising your garden will help to prevent this from happening and will also allow you to train your plants to grow in specific directions.
Another thing to consider is pruning. With hydroponics, your plants can grow extremely fast. This means you need to be diligent about pruning. Removing all the bottom foliage and topping your plant before switching to its flowering cycle will allow your top colas (the large, topmost buds) to receive all the energy they need.
Growing hydroponically does require that you invest a good amount of time and money into developing your system prior to actually starting your garden. Additionally, you’ll want to make sure your system works effectively and your nutrients are high quality so that your plants will flourish. Once you gain a knack for hydroponics, you’ll be on your way to producing world-class cannabis that is well worth the effort.
Have you ever tried hydroponic growing techniques before, either for cannabis plants or other grows? Share your advice, tips, and questions in the comments section below!